Our ‘HD voice’ featured section is dedicated to bringing you all you need to know about wideband audio. We’ll tell you exactly what it is, where and how to get it, how it is incorporated into our OnSIP service, and even help dispel some common misconceptions.
Quick Intro to HD Voice and Wideband Technology
There are actually many names and many different examples of wideband audio technology. It is most commonly referred to as ‘HD voice’, a term popularized by telepresence and voice communications provider Polycom. ‘HD voice’ as used by Polycom actually refers to the combination of their software and hardware design as well as the implementation of wideband technology. Other players in the industry may have other branded names—for example, Aastra calls their HD VoIP audio Hi-Q.
To avoid confusion in this section, we will refer to all the different implementations of wideband technology to bring about higher voice quality as simply ‘HD voice’.
First, let’s define some key terms that you’ll probably be seeing a lot of in these sections.
In VoIP, a codec is used to convert analog voice signals into the equivalent digitally encoded version. There are quite a few different codecs, each of which may have different bandwidth and computational requirements.
Usually end user devices such as IP phones and softphones will each support several different codecs. When two of these devices try to talk to each other, they will negotiate which codec to use by looking at which ones they have in common. You can think of codecs as the different types of audio files on your computer. Just as a .wav player would not be able to play an .mp4, an IP phone would not be able to successfully communicate with another end user device if they did not at least share one codec (unless they go through a gateway).
Wideband audio technology uses a wideband codec, which uses a greater frequency range of the audio spectrum than conventional telephone calls. The PSTN and a majority of VoIP codecs capture at 8 khz, while a wideband VoIP implementation might capture at 16 khz.
G.722 is a freely available (it was introduced in 1988 and the patent has since expired) standard wideband codec that samples audio data at a rate of 16 kHz.